Brush holder



April 4, 1967 I B. SATKUNAS 3,312,345

BRUSH HOLDER Filed Feb. 8, 1965 IN VEN TOR.

BRUNO SA TKUNA S United States Fatent O 3,312,845 BRUSH HOLDER BrunoSatkunas, Lexington, Ohio, assignor to Dominion Electric Corporation, acorporation of Ohio Filed Feb. 8, 1965, Ser. No. 430,919 10 Claims. (Cl.310-247) My invention relates to devices for holding the brushes of anelectric motor in operating position.

An object of my invention is to provide an improved construction of abrush holder readily and easily mounted to the frame of the motor andwhich is readily connected to the terminals of electric conductors orwires.

Another object is the provision of an improved brush holder ofinsulating material having structural features which aid in the readyand rapid assembly of the brush holders with the motor and whichsecurely hold the brush holder in position on the motor.

Another object is the provision for obtaining a good sliding fit betweenthe brush and the holder thereof which permits easy movement of thebrush axially of the holder with a minimum of friction.

Another object is the provision of a brush holder giving improvedelectrical insulating characteristics, reduced frictionalcharacteristics for movement of the brush therein and also beingparticularly adapted for the ready assembly of the brush in the holderand the mounting of the holder to the frame.

Another object is the provision for an economical construction of brushholder and which also provides economies in the operation of assemblingthe brush holder with the motor frame.

Other objects and a fuller understanding of the invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawing, in which:

FIGURE 1 is a longitudinal sectional view through a typical electricmotor to which my invention has been applied;

FIGURE 2 is a side View of the motor shown in FIG- URE l and showing thebrush holder on one side of the motor;

FIGURE 3 is an enlarged view of one side of the brush holder removedfrom the motor;

FIGURE 4 is an enlarged view of the opposite side of the brush holderremoved from the motor; and is anview looking in the direction of thearrows 44 of FIG- URE 6;

FIGURE 5 is an enlarged end view of the brush holder and looking in thedirection of the arrows 5-5 of FIG- URE 3; and

FIGURE 6 is a cross-sectional enlarged view of the brush holder removedfrom the motor and looking in the direction of the arrows 6-6 of FIGURE3.

The typical electric motor to which my invention has been applied asshown in FIGURES 1 and 2 has been indicated generally by the referencecharacter 11. It is to be understood that the invention is equallyapplicable to generators and dynamo-electric machines utilizing brushesmaking contact with the commutator, or other rotatable electric contactelement. In this specification and claims, the invention will bereferred to as related to a motor, as an electric motor is the mostcommon and typical use for the invention. It is to be understood,however, that the word motor as usedherein will include generators ordynamo-electric machines.

The motor 11 has a frame 12 having parallel frame members upon which iscarried the stator 13 which in turn carries the usual stator winding 14.Carried by the frame 12 adjacent its opposite ends are the bearings 18and 19 which rotatably carry the rotor 15 for the rotation of the rotor15 relative to the stator. The usual rotor windings 16 are carried bythe rotor 15. A driving shaft 17 extending through the rotor 15 andprotruding from the motor frame 12 is rotated by the rotor uponelectrical energization of the motor. Mounted on the motor shaft 17 soas to rotate therewith is the usual commutator or segmented collector20. The commutator 20 has the usual function in such motors and thelike.

Carried by the frame 12 and disposed radially outward of the commutator20 are a pair of brush holders 21, the two brush holders 21 being ondiametrically opposite sides of the commutator. One brush holder 21 iscarried by one frame member of frame 12 and the other brush holder iscarried by the opposite frame member of the frame 12. Each brush holder21 is composed of a material of high electrical insulatingcharacteristics, the provision of a good bearing surface for minimizingfriction in the sliding of a brush axially therein, required resilientyieldability to provide the slight resilientyielding herein describedfor the holder 21, and which is relatively cheap and easily fabricated,such as bymolding. Such materials having this combination of desirablecharacteristics are of the class including nylon and lexan. Thepreferred material that has been found suitable for the purposes of mybrush holder is molded nylon.

The brush holder 21 has four rectangular sides 21A which provide atubular structure of rectangular crosssection, in this instance, squarecross-section. At the inner end of the holder 21, that is, the end to bedirected toward the commutator, the walls are chamfered to provide thechamfered end 21B. The portion of the holder on the inner side of theframe members is referred to as the first or inner end portion and theportion of the holder extending outwardly of the frame in a directionaway from the commutator is referred to as the second or outer endportion. On the first or inner end portion of the brush holder, there isa raised detent portion 21D. In the embodiment illustrated, there is adetent portion 21D on the opposite outer wall of the holder 21. Thedetent portion 21D has a fiat surface parallel to the axis of the holder21 and an inclined camming surface 21C extending from adjacent the innerend of the holder to the flat surface of the'detent portion. Theinclined camming surface 21C is on the same incline as the outer surfaceof the chamfered end whereby the inclined camming surface 21C is ineffect a continuation of the inclined surface provided by the chamferedend 21B.

It is to be noted that the detent portion 21D on diametrically oppositesides of the holder 21 have Widths that are substantially less than thewidth of the respective wall 21A of the holder. By having the detentportion 21D spaced from the opposite parallel walls joining the wallscarrying the detent portion 21D, the respective walls 21A from which thedetent portions 21D extend may more readily resiliently yield orcollapse upon lateral pressure on the detent portions 21D toward theaxis of the holder 21.

Spaced in an axial direction from the detent portions 21D and extendinglaterally outward from one of the walls 21A is a boss or raisedprojection 21E. In the embodiment illustrated, the boss 21B is on thesame Wall 21A from which extends one of the detent portions 21D. Thelateral extension of the boss 21E from the wall 21A is substantiallygreater than that of the detent portion 21D as seen in FIGURES 5 and 6.It is to be noted that there is a space in an axial direction between acommon plane through the detent portions 21D closest to the boss 21E andthe boss 21E. This niche or space 21H between the boss 21B and a detentportion 21D is at a location on the holder having substantially the samecross-sectional dimension as the main portion of holder 21.

Adjacent the outer end of the second or outer portion of holder 21,there are two aligned slits or openings 21F in, one wall 21A and 216 inan opposite wall 21A. These slits 21F and 21G accommodate the spadeterminal 24 connectedto a conductor or wire 25. As seen in the drawing,the spade terminal 24 has a relatively small forward end 24A and arelatively wide rearward end 243. The slit 21F is relatively short so asto accommodate the small end 24A of the spade terminal and has a widthas Well as length causing the edges of the holder around the slit 21F tosnugly and frictionally engage or interlock with the small end portion24A of spade terminal 24. As better seen in FIGURE 3, the slit 21F isenlarged at a location intermediate its ends so as to better permit theedge portions of slit 21F to resiliently flex upon forcing of the smallend 24A into the slit 21F.

The slit 21G in the opposite wall of the holder has a length toaccommodate the wide portion 24B of the spade terminal. Its length andwidth are such as to snugly embrace and frictionally engage the portion248 when inserted therein. The slit 21G also has an enlarged portionintermediate its ends as seen in FIGURE 4 to facilitate resilientflexing of the edge portions of the slit 21G.

To mount the holder 21 in the frame 12, a holder without brush or otherparts therein is pressed through the holder-accommodating opening in aframe member from the outside of the frame in a direction toward thecommutator 20. The chamfered end 21B first enters this opening and helpsin leading or introducing the holder into the opening. The opening hasan internal cross-sec-' tion closely complementing the outside dimensionof the holder 21 at the location of its rectangular shape. Upon forciblypressing the holder 21 through the opening toward the commutator, theinclined camming surfaces 21C engage opposite edge portions of theopening and resiliently yield and partially but slightly collapse theholder so as to enable the detent portions 21D to pass through theopening to the position illustrated in FIG- URES 1 and 2. When in thisposition, the holder, being resiliently yieldable, again causes thedetent portions 21D to move out to their normal position shown inFIGURES 1 and 2. The detent portions 21D thus provides shoulders whichabut the inner side of the respective frame memher and preventwithdrawal of the holder from the frame. In the same movement, the boss21E has moved so as to abut the outer side of the frame at the openingand thus stops or prevents further or continued movement of the holdertoward the commutator. The holder is thus firm- 1y locked to the framemember in the position illustrated in FIGURES 1 and 2. The operation, ofcourse, is the same for the holders 21 of the opposite sides of theframe. After the holder is so mounted to the frame, a brush 22 usuallymade of carbon, or sometimes of copper or other alloy of electricalconducting characteristics, is moved axially into the holder 21 from theouter end thereof. The cross-sectional dimension of the brush 22 is suchthat it slidably interfits with the inner wall of the holder 21. Thenature of the nylon or equivalent material is such as to provide a goodbearing engagement for the brush 22 and this facilities its readysliding movement toward and away from the commutator 20. 7

After the brush is inserted, such as to its position shown in FIGURE 1,then a metal coil spring 23 is placed within the holder from the outerend thereof. The spring 23 is compressed by a suitable tool and while socompressed, the spade terminal 24 is mounted transversely in the holderby forcibly thrusting it through the aligned slits 21F and 216, thedirection of movement being from the larger slit 21G toward the smallerslit 21F. After the spade terminal is in the position shown in FIGURES 1and 2, the tool compressing the spring 23 is withdrawn and the spring 23then abuts against the spade terminal 24. The bias of the spring 23 issuch as to resiliently urge the brush 22 Q a d the commutator 20. Themetal 4 spring 23 also provides electrical connection between the spadeterminal 24 and the brush 22.

It has been found that the invention above described improves theeficiency of brush movement and facilitates the ready assembly of thebrush and brush holder with the motor.

The present disclosure includes that contained in the appended claims,as well as that of the foregoing description.

Although this invention has been described in its preferred form with acertain degree of particularly, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thecombination and arrangement of parts may be resorted to withoutdeparting from the spirit and scope of the invention as hereinafterclaimed.

What is claimed is:

1. In an electric motor having a frame, said frame havingbrush-accommodating openings of rectangular crosssection extendingtherethrough, a commutator rotatably carried by the frame and positionedinwardly from said brush-accommodating openings, electrical conductorshaving spade-type terminals of a shape having a forward end of smallerWidth than the rearward end, the terminals being adapted to beelectrically interconnected with said commutator, and brushes adapted toengage and electrically connect with said commutator, the improvement ofbrush holders for carrying the respective brushes in engagement withsaid commutator, each said holder comprising an open-ended tubularstructure of rectangular cross-section complementarily interfitting in asaid brushaccommodating opening and having a first portion extendingfrom an inner side of the frame toward the commutator and having asecond portion extending from an outer side of the frame away from thecommutator, said holder on opposite sides of said first portion thereofhaving projections extending outwardly from the planes of said oppositesides a greater distance than the corresponding sides of said opening toengage on said inner side of the frame and prevent withdrawal of theholder outwardly from the frame away from the said commutator, saidprojections each having an inclined camming surface extending from theplane of the respective side of the structure adjacent the inner end ofsaid first "portion to the maximum extent of said each projection tocammingly lead the said projection into a said opening upon pressing thesaid first portion of structure into the opening toward said commutator,said structure being composed of a resiliently yieldable material of theorder of nylon and lexan to permit the structure to resiliently yield inpressing the said first portion carrying said projection into saidopening, said material being of high electrical insulating property toinsulate the brush from the frame, said structure having a bossextending from a side thereof, the boss having a shoulder spaced fromsaid inner side of the frame and abutting said frame on the outer sidethereof to prevent further movement of said structure through theopening toward the commutator, said structure having ex-. tendingthrough opposite sides thereof adjacent the outer end of said secondportion aligned open spaces for receiving a said spade terminalextending through the open spaces transversely of the structure, one ofsaid open spaces being shorter than the other and snugly engaging thesmaller forward end of the spade terminal and the other of said openspaces snugly engaging the larger rearward end of the spade terminal,the material of the structure resiliently yielding to permit insertionof the spade terminal into said aligned open spaces and to restrain thespade terminal against withdrawal from the aligned open spaces, saidholder having a bore for accommodating an axially aligned electric brushtherein in sliding engagement with the inner walls of the holder and forpermitting the brush to extend axially of the holder from the holdertoward and against the commutator, said bore also accommodating a metalcoil spring therein between, and in engagement with, said brush and saidspade terminal in said aligned open spaces, thecoil spring resilientlybiasing the brush toward the armature and providing electricalconnection between the brush and spade terminal.

2.. The structure as claimed in claim 1 and in which the inner end ofthe first portion of said structure is chamfered to cammingly lead thesaid first portion into the respective opening toward said commutator.

3. The structure as claimed in claim 2 and in which said aligned openspaces in the second portion of the structure are extendedlongitudinally of the structure at a location intermediate the ends ofthe respective open spaces to aid resilient flexing of the sides of theopen spaces upon insertion of the spade terminal into the aligned openspaces.

4. A brush holder for an electric motor having a frame, a commutatorrotatably carried by the frame, the frame having an opening therethroughdirected radially of the armature for accommodating the brush holder,said brush holder comprising a tubular structure adaptedto hold a brushaxially movable relative thereto and protruding axially therefrom towardand in electrical engagement with said commutator, said tubularstructure being of electrical insulating material and resilientlyyieldable to provide slight yieldable flexing under restraint andassuming its normal shape, said structure being partially insertablethrough said opening in the frame to extend a first end portion thereoffrom an inner side of the frame toward the commutator and an oppositeend portion thereof from the outer side of the frame away from thecommutator, said structure having a projection extending from a sidethereof to engage the inner side of the frame for preventing withdrawalof the structure from the opening away from the commutator, saidprojection having a slanted camming surface for leading the projectioninto the opening upon pressing the structure into the opening toward thecommutator, said projection having a width less than the width of saidside from which the projection extends to facilitate the resilientyielding of the said side of the structure inwardly of the structureupon pressing of the projection with said first portion of the structureinto said opening, said structure having a boss extending outwardly of aside thereof and spaced axially of the structure from a transverse planethrough said projection to engage the outer side of the frame andprevent movement of said second portion of the structure through theopening toward the commutator, whereby the frame may be lockedintermediate the said transverse plane through the projection and atransverse plane through the boss, said structure having transverselydisposed aligned holes through the second portion thereof foraccommodating a spade terminal of an electrical conductor, the structurebeing adapted to accommodate a metal coil spring therein between a brushtherein and said spade terminal for bias ing the brush toward thecommutator and providing electrical connection between the spadeterminaland brush.

5. A holder as claimed in claim 4 and in which said structure iscomposed of nylon.

6. A holder as claimed in claim 4 and in which said structure iscomposed of lexan.

7, An improved brush holder for an electric motor having a frame and acommutator rotatably carried by the frame, the frame having a framemember spaced from said commutator and parallel to the axis thereof,said frame member having an opening extending therethrough from a firstside toward the commutator to a second side away from the commutator foraccommodating the brush holder in juxtaposition to the commutator, saidholder comprising an elongated structure having a bore extendingtherethrough and an outer wall generally complementing the inner wall ofsaid opening, said structure being composed 91 a material having theelectricalinsulating, resilient yieldability, bearing characteristicsand strength of nylon, the structure being insertable through saidopening in the frame from said second side of the frame toward saidcommutator to provide a first portion extending from said first sidetoward the commutator and a second portion extending from said secondside away from the commutator, said first portion having a detentvportion extending laterally outward from said outer wall of thestructure to engage said first side of the frame and prevent withdrawalof the structure from the opening in a direction away from thecommutator, said detent portion having an inclined camming surfaceextending on its end toward the commutator to aid the detent portionenter said opening upon the insertion of the structure into the openingfrom said second side of the frame, said second portion having a stopportion extending laterally outward from the outer wall of the structureto engage said second side of the frame and prevent further movement ofthe structure through said opening toward the commutator, said secondportion having slits extending through opposite walls thereof forreceiving a spade terminal inserted therethrough transversely of thestructure, the edges of said slits being formed to resiliently yieldupon insertion of the spade terminal therethrough and to bind upon thespade terminal therein, said bore in the structure being adapted toaccommodate an electric brush slidable axially thereof and protrudingfrom said first portion thereof into engagement with the commutator anda metal coil spring interposed between the brush and spade terminaldisposed through said slits, said spring biasing the brush toward thecommutator and providing electrical connection between the brush andspade terminal.

8. A holder as claimed in claim 7 and in which the walls of thestructure at the end directed toward said commutator are chamfered toaid in leading said end into the opening upon the insertion of thestructure therethrough from said second side, the chamfered wallcontinuing on the incline of said inclined camming surface of the detentportion to provide a substantially uninterrupted inclined surface, andin which said detent portion has a width substantially less than thewidth of said outer wall of the structure from which it extends tofacilitate the resilient yielding of said wall inwardly of the structureupon the structure and detent portion passing through said opening.

9. A holder as claimed in claim 8 and in which said slits have enlargedportions intermediate their respective ends to aid in the resilientflexing of the edges of the slits upon insertion of the spade terminaltherethrough.

10. A holder as claimed in claim 8 and in which said structure includestwo detent portions extending in opposite directions laterally of thesaid outer walls, respectively, and in which said stop portion extendssubstantially a greater distance from a said outer wall than said detentportions.

References Cited by the Examiner UNITED STATES PATENTS 2,482,921 9/1949Malchus 310-247 2,548,631 4/1951 Stapleton 310-247 2,914,689 11/1959Weeks 310247 2,989,656 6/1961 Herbst 310247 3,239,704 3/1966 Miller310-247 FOREIGN PATENTS 21,568 1/1909 Great Britain. 5,672 9/ 1915 GreatBritain. 77,415 3/ 1955 Netherlands.

MILTON O. HIRSHFIELD, Primary Exan'zfner.

D. F. DUGGAN, Assistant Examiner.

1. IN AN ELECTRIC MOTOR HAVING A FRAME, SAID FRAME HAVINGBRUSH-ACCOMMODATING OPENINGS OF RECTANGULAR CROSSSECTION EXTENDINGTHERETHROUGH, A COMMUTATOR ROTATABLY CARRIED BY THE FRAME AND POSITIONEDINWARDLY FROM SAID BRUSH-ACCOMMODATING OPENINGS, ELECTRICAL CONDUCTORSHAVING SPADE-TYPE TERMINALS OF A SHAPE HAVING A FORWARD END OF SMALLERWIDTH THAN THE REARWARD END, THE TERMINALS BEING ADAPTED TO BEELECTRICALLY INTERCONNECTED WITH SAID COMMUTATOR, AND BRUSHES ADAPTED TOENGAGE AND ELECTRICALLY CONNECT WITH SAID COMMUTATOR, THE IMPROVEMENT OFBRUSH HOLDERS FOR CARRYING THE RESPECTIVE BRUSHES IN ENGAGEMENT WITHSAID COMMUTATOR, EACH SAID HOLDER COMPRISING AN OPEN-ENDED TUBULARSTRUCTURE OF RECTANGULAR CROSS-SECTION COMPLEMENTARILY INTERFITTING IN ASAID BRUSHACCOMMODATING OPENING AND HAVING A FIRST PORTION EXTENDINGFROM AN INNER SIDE OF THE FRAME TOWARD THE COMMUTATOR AND HAVING ASECOND PORTION EXTENDING FROM AN OUTER SIDE OF THE FRAME AWAY FROM THECOMMUTATOR, SAID HOLDER ON OPPOSITE SIDES OF SAID FIRST PORTION THEREOFHAVING PROJECTIONS EXTENDING OUTWARDLY FROM THE PLANES OF SAID OPPOSITESIDES A GREATER DISTANCE THAN THE CORRESPONDING SIDES OF SAID OPENING TOENGAGE ON SAID INNER SIDE OF THE FRAME AND PREVENT WITHDRAWAL OF THEHOLDER OUTWARDLY FROM THE FRAME AWAY FROM THE SAID COMMUTATOR, SAIDPROJECTIONS EACH HAVING AN INCLINED CAMMING SURFACE EXTENDING FROM THEPLANE OF THE RESPECTIVE SIDE OF THE STRUCTURE ADJACENT THE INNER END OFSAID FIRST PORTION TO THE MAXIMUM EXTENT OF SAID EACH PROJECTION TOCAMMINGLY LEAD THE SAID PROJECTION INTO A SAID OPENING UPON PRESSING THESAID FIRST PORTION OF STRUCTURE INTO THE OPENING TOWARD SAID COMMUTATOR,SAID STRUCTURE BEING COMPOSED OF A RESILIENTLY YIELDABLE MATERIAL OF THEORDER OF NYLON AND LEXAN TO PERMIT THE STRUCTURE TO RESILIENTLY YIELD INPRESSING THE SAID FIRST PORTION CARRYING SAID PROJECTION INTO SAIDOPENING, SAID MATERIAL BEING OF HIGH ELECTRICAL INSULATING PROPERTY TOINSULATE THE BRUSH FROM THE FRAME, SAID STRUCTURE HAVING A BOSSEXTENDING FROM A SIDE THEREOF, THE BOSS HAVING A SHOULDER SPACED FROMSAID INNER SIDE OF THE FRAME AND ABUTTING SAID FRAME ON THE OUTER SIDETHEREOF TO PREVENT FURTHER MOVEMENT OF SAID STRUCTURE THROUGH THEOPENING TOWARD THE COMMUTATOR, SAID STRUCTURE THROUGH THE TENDINGTHROUGH OPPOSITE SIDES THEREOF ADJACENT THE OUTER END OF SAID SECONDPORTION ALIGNED OPEN SPACES FOR RECEIVING A SAID SPADE TERMINALEXTENDING THROUGH THE OPEN SPACES TRANSVERSELY OF THE STRUCTURE, ONE OFSAID OPEN SPACES BEING SHORTER THAN THE OTHER AND SNUGLY ENGAGING THESMALLER FORWARD END OF THE SPADE TERMINAL AND THE OTHER OF SAID OPENSPACES SNUGLY ENGAGING THE LARGER REARWARD END OF THE SPADE TERMINAL,THE MATERIAL OF THE STRUCTURE RESILIENTLY YIELDING TO PERMIT INSERTIONOF THE SPADE TERMINAL INTO SAID ALIGNED OPEN SPACES AND TO RESTRAIN THESPADE TERMINAL AGAINST WITHDRAWAL FROM THE ALIGNED OPEN SPACES, SAIDHOLDER HAVING A BORE FOR ACCOMMODATING AN AXIALLY ALIGNED ELECTRIC BRUSHTHEREIN IN SLIDING ENGAGEMENT WITH THE INNER WALLS OF THE HOLDER AND FORPERMITTING THE BRUSH TO EXTEND AXIALLY OF THE HOLDER FROM THE HOLDERTOWARD AND AGAINST THE COMMUTATOR, SAID BORE ALSO ACCOMMODATING A METALCOIL SPRING THEREIN BETWEEN, AND IN ENGAGEMENT WITH, SAID BRUSH AND SAIDSPADE TERMINAL IN SAID ALIGNED OPEN SPACES, THE COIL SPRING RESILIENTLYBIASING THE BRUSH TOWARD THE ARMATURE AND PROVIDING ELECTRICALCONNECTION BETWEEN THE BRUSH AND SPADE TERMINAL.